JPS62502317A - Cooled hollow fiber - cross flow type separator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Cooled Hollow Fiber Cross Flow Separator Field of the Invention The present invention provides cooling of porous hollow fibers in a cross-flow separator. Regarding rejection.

Conveniently, the present invention provides for the recovery of finely divided solids from suspensions. , regarding the use of hollow fibers. However, the present invention Solid concentrator applied to cross-flow filters and other devices using empty fibers It should be understood that this is not limited to.

Background technology The problem of recovering multiple fine solids from suspensions is to recover clear liquids from suspensions. This is complementary to that.

For a recent detailed discussion of cross-flow microfiltration.

In the June 1984 issue of The Chemical Engineer, R. Bertella, H. Provided by Steven and M. Metcalfe.

Economical and capable of handling heavily soiled and multiple solids without the aid of filters. coveted. This fouling problem has long been recognized and In order to avoid reusing clarified liquid for liquid, Several attempts have been made to replace the gas.

Gas backflow inside and outside the membrane can be prevented by ultrafine pore-shaped filters such as reverse osmosis membranes and ultrafine filters. In Luther, this is not possible. This is because 1 is necessary to overcome surface tension. The pressure is far greater than the strength of ordinary hollow fibers used for this purpose. This is because it is Gas bubbles passing through such a membrane are caused by pins within the membrane. This indicates the presence of hole defects.

Therefore, the present invention does not provide for reverse osmosis or true ultrafilter applications. .

The present invention is 0.001 to 10 microns larger than the aforementioned ultra filters. relates to a microfilter having pores within the range of . Usually, the size of each pore is , the clear water is set free from all visible dirt. clear water The dirt contains particles larger than the pores and particle size, and is known as It appears according to optical laws.

Early microfilters were suspended by a Brownian action that was neither sparging nor dispersing. Not only does it not penetrate within a similar pore size range by means of a blind sieve. Because it deals with small molecules, it gets dirty very quickly.

One conventional technology developed to solve this problem is the backflow of clarified liquid into and out of the membrane. By using a hydrophilic microfilter in the cross-flow mode of It was.

The high cross-flow velocity creates a small internal surface opposite a large external surface of the Phi^−. A feedstock suspension suitable for the pores of the filter surface was required. Therefore, the backflow pressure is - had to be restricted to avoid damage to the This small filter table surface will reduce the output, which is often not an effective solution to the problem. It didn't happen.

Other developed prior art is 1 Japanese Patent Publication No. 53 (1978)-10sa There is No. A2, and here we use hydrophilic polyvinyl alcohol (PVA) fiber. The hollow fiber bundle in the shape of a candle is made of It was in an unstable state during the large backflow for 1 minute. This Japanese specification is described here. This type of filter "candle" consists of an elongated hollow pot with one end closed. Compared to cross-flow type shell and tube filters, which are composed of It is similar to Mari's dead-end filter.

The aforementioned new water-based “polyvinyl alcohol (PVA)” type polymer has large pores. The development of the "candle" shape of hollow fibers was covered by British Patent No. 2.120,95. It is disclosed in No. 2. The style of this fiber bundle is as described in the Japanese Patent Publication No. 53 (1978)-108882 to avoid fiber damage and entanglement. They are housed in an open sleeve and the fibers are loosely taped in order to Although it was suppressed by winding the gas with a plastic wrap, the gas backflow lasted for 5 minutes.

Prior art techniques for backflow cleaning of porous hollow fibers using liquids and gases are extremely This is because the host operates quickly in isolation mode. This case concerns a cooled cross-flow separator that handles dry feedstock.

Cooling of hot fibers by blowing air onto them or by water evaporating from them is , which encompasses a thermal principle similar to wringing out a towel soaked in water to cool it down. are doing.

However, cooling the hot separator device to a precise temperature in a single method The problem with using these thermal principles in an accurate and rapid way for It is something. The most notable thing is that air penetrates the pores through which water passes. This was to cool the air evaporatively. Typically, the temperature gradient formed in a porous material that is not suitable for On the other hand.

The hottest spot on the fiber has the highest vapor pressure and heats up fastest. temperature and thus achieve temperature uniformity.

Disclosure of invention The present invention particularly provides for cleaning of the drawn fibers to be achieved by backflow of gas and water. Rapid porous hollow fiber bundles in cross-flow separators handling hot suspensions The present invention relates to methods and means for cooling. The rapid cooling of this fiber The method of the present invention is integrated with other operating cycles of the It is applied to suspensions containing quality.

The high temperature operation of cross-flow concentrators dramatically increases the production rate of each solids. However However, the cycle of reflux is.

is required to clean such separators and at such temperatures. The explosive pressure of some fibers is excessive and therefore the fiber cooling is required.

Preferably, solids are washed away from within the concentrator shell and from the fiber surface. , the surface tension within some large pores spreads over the surface of the fiber. The gas at a pressure exceeding capillary pressure removes dirt from all pores of the fiber. to expand the flexible pores without damaging the hot fibers. The reflux is carried out with clarified liquid at a pressure that is carefully and optimally regulated for this purpose.

Other considerations for high temperature operation of cross-flow concentrators.

The temperature of the fiber is lower than the suspension feed outside the fiber for the next complete cycle. The rapid return of flexible pores to their original size before reinforcing the surface must be adjusted so that

The pressure required to achieve backflow depends on the flexibility of the fiber in case of liquid backflow. is set by the pore size and surface tension for gas backflow. porous po For use in the Rimmer fiber microfilter range, these pressures are higher than the filtration or concentration pressure. Therefore, the hot fiber before reflux is Rapid repeated cooling of the bars is required for advanced production equipment.

Flexible. and added to the microporous hollow fiber, and Each solid object (5 olds) held in a bar or other shell is pressurized into a gas and released by pressurized backflow of clarified liquid due to backflow of water.

There, the hollow fibers are cooled before being subjected to pressurized backflow. A method for processing a suspension is provided.

According to another means of the present invention, each solid substance in the suspension is concentrated by the following steps. (1) A flexible and microscopic structure within the shell or housing is provided. By adding a suspension to the outer surface of microporous hollow fibers: (a) Some suspension is extracted as clear liquid from multiple fiber holes. It penetrates each wall of each fiber.

(b) at least some solid matter is on or in the fiber or otherwise in the fiber; In the well, unretained solids are removed from the shell along with the remaining liquid. together, withheld; (ii) Stop the flow of the suspension and cool the hollow fibers. and.

GiD, multiple fixings retained from the shell by adding through the fiber holes. Release the body object: (a) by penetrating substantially all the pores with the pressurized liquid; Substantially all pores are expanded to wash away all retained solids; (b) The pressurized gas releases all solid matter retained within these pores and At the same time as expanding these pores, cleaning the outer wall of the fiber and removing everything from the inside of the shell. through large pores in order to transfer solid matter to an external collection area.

By displacing the liquid in all holes with gas under the pressure of the fish body, all of the fibers are removed. Introduced to wash the length. This shell is a trap gas that crosses the bubble point. so that gas cannot flow through the fiber wall due to the pressure of the It is sealed with a relatively incompressible raw material liquid. This sealing means that the trapped gas can enter from the main inlet. The solution is such that even the most distant parts have a substantially constant escape through the fiber wall. as a result, preferential cleaning of the pores near the gas inlet is minimized. There is.

Gas is applied to the outer surface of each fiber and each fiber is cooling by passing the gas through the Rejected.

Brief description of the drawing In order to understand the present invention more deeply and clarify its effects, it will be explained below with reference to one drawing. do.

Figure 1 is a schematic diagram of a hollow fiber cross-flow concentrator in its concentration or operating mode. Figure 2 is the same as Figure 1 to show the concentrator in backflow cleaning mode. A schematic configuration diagram of Figure 3 shows concentrator clarified liquid flux versus time in a hollow fiber cross-flow concentrator. A graph showing the

Figure 4 shows a graph of temperature versus trans-fiber strain pressure in a porous hollow fiber. centre, FIG. 5 is a schematic diagram of a system for processing suspensions according to one embodiment of the present invention. The diagram, Figure 6, shows the suspension treatment of Figure 5 showing the dependence of filtered water flux on temperature. Graph of temperature versus water flux in a mechanical system.

Figure 7 shows the time versus time for the suspension processing system of Figure 5 with feeding at elevated temperatures. Hollow fiber cross-flow type concentration shown in graphs of clear liquid flux in Figures 1 and 2. The compressor 10 includes a car 1-1 containing a bundle of hollow, porous polymer fibers 12. It has an IJ shell 11. In this case, each fiber is made of polypropylene. The average pore size is 0.2 microns and the wall thickness is 200 microns. The hole diameter is 200 microns. There are 3000 hollow holes in this bundle 12. depending on the individual fiber area, this number may vary depending on the operating requirements. Can be changed upon request.

The polyurethane injection mixtures 13 and 14 are applied without closing the ends of the shell 11. , and holds both ends of the fiber 12 without destroying these holes. . The suspension to be concentrated passes through a suspension feed port 15 and then through each hollow fiber. It is fed into the shell 11 through each of the 12 outer walls. Some of the feed suspension It passes through the wall of fiber 12 and enters the hole of each fiber.

It comes out as a clear liquid through the hole outlet 16.

The remaining raw material suspension and some removed particles (species) are It flows between the fibers 12 and exits the shell 11 via the outlet 17. grains taken out The rest of the children are retained in or on the fiber or held within the shell. child In this case, even if clear liquid is drawn out from both ends of each hole, high flux conditions However, during the operating mode of the concentrator shown in Figure 1, the large inlet port 18 is closed. Ru.

Outlet 1 is used to remove particles trapped within each fiber or shell. 6 is closed and the flow of clear liquid is stopped. The pressurized clarified liquid is then substantially expand all pores and wash them with clear liquid to at least the entire pore volume. For this purpose, it is guided into the hole via the hole entrance port 18. Cleaning with clarifying liquid is completed. After that, the compressed gas passes through the large robot 18 and continues along the holes of each fiber 12. are guided into the raw material suspension through the walls of each fiber. Concentrated flow is a clear liquid It may have been washed out from within the pores of each fiber or accumulated on each outer wall. 1. Generates intense bubbling to clean all particles from the shell. live.

An embodiment according to the invention that is particularly suitable for elongated fibers In order to prevent the gas from escaping through each pore of each fiber at this stage, a limited After opening the hole exit boat 16 for a period of time, the compressed gas passes through the inlet 18 to each fiber. - Introduced along hole 12. This liquid-filled shell is located at the shell inlet 1. 5 and shell outlet 17. For example, if the gas pressure Even if the gas rises above the normal bubble point of the fiber wall, it will penetrate the porous wall. cannot, because the liquid inside the shell is relatively incompressible. Therefore, it is. A reservoir of high pressure gas is thus accumulated within the fiber hole.

The shell outlet 17 is opened to allow gas to pass through the pores along the entire length of each fiber. be done. Initially, the bubble gas generation is virtually constant, but eventually each thin Due to the pressure drop that occurs along the fiber, the end remote from the large inlet port 18 At this point, the force becomes 1.

In special cases, after carrying out the pressurization and decompression gas operations described above, the hole port 16 It is desirable for gas to pass through and 18.

Oversized particles from the feedstock suspension may not penetrate into or through the enlarged pores. The pores are enlarged by the gas, restoring them to their original size so that they cannot The feedstock suspension filtrate after gas backwashing for sufficient time to allow pores to form. Preferably, recovery of rows is delayed.

Figure 6 shows the effect of solids release described in relation to Figure 2 in view of the production rate of clear liquid. It shows. Curve A shows the decreasing trend of clear liquid flux versus time excluding solids release. and curve C therein shows the cleanliness after each mixed liquid and gas backflow cycle. It shows the recovery of clear fluid flux. The release of solids is almost entirely dependent on the clarified liquid flux. However, the decrease in efficiency is due to the extended time despite continuous release. Precipitates that exceed the width (period) are uniformly removed by chemical cleaning. can do.

The high level of tolerance that the fibers have under the pressures required for each aspect of the entire process. It has been noted that high power often indicates that the concentrator is operated at high temperatures. Ta. However, these pressures change and the direction of pressure on the fiber changes. Furthermore, there are extremely different stresses at each location and direction on the fiber. is imposed. These are extremely closely related to this invention. I mentioned earlier What is the biggest stress?

Generated from the high pressure used during backwashing.

As is well known, the mechanical strength of hollow fibers made of polymers varies substantially with temperature. It changes with The curve in Figure 4 represents the point where pressure is applied to the outside of the fiber. Represents the decompression of polypropylene fibers. The pressure at which the fiber collapses is high It decreases at higher temperatures.

Curve E in Figure 4 shows that the polypropylene fiber breaks when pressure is applied to the hole. It shows the pressure.

This failure pressure decreases at high temperatures. fibers are sufficient for high backflow pressures. The suspension was treated at an elevated temperature T(1) for failure strength or insufficient failure strength. In some cases it may be advantageous to use rapid cooling means. Then each fiber The failure pressure is reduced to P(2) before applying the maximum backflow pressure. 1) to P(2). However, a decrease in temperature causes pore expansion to must be controlled to make it possible.

The cooling method of the present invention applied to a cross-flow hollow fiber concentrator can be applied to multiple It is possible to use the system shown in FIG. . In the cross-flow concentration mode, the pump 38 supplies the suspension tank via the pump suction line 39. The suspension is drawn from the tank 27 and passed through the inlet pressure valve 37 to the suspension stop solenoid valve. A cross-flow concentrator 20 is fed via a suspension inlet line 29 with 41 .

The raw material suspension passes over the surface of the hollow fibers in the cross-flow type concentrator 20, and The clear liquid is passed through each fiber to be supplied to the clear liquid outlet line 21. Pass into each hole. The clarified liquid in line 21 is activated by solenoid 47a. Clear liquid lifting cylinder 47. Clarifying liquid controlled by solenoid 22a It passes through a control valve 22 and a flow sensor 32 and is collected at a clear liquid collection point.

The flow of clear liquid to this line 23 is prevented by a check valve 51. Ru.

The concentrated raw material suspension from the cross-flow type concentrator 20 is passed through a check valve 35 and a solenoid operated Controlled by solenoid 30a via dynamic shell sealing valve 55 (when compatible) 3-way valve 30 is supplied to line 28 which is distributed by a three-way valve 30. This valve 30 having output passages (a) and (b) for supplying the liquid tank 27 and the collection point respectively; There is.

In the concentration mode, the valve 30 becomes the output passage (a).

The concentrated raw material suspension passes through the back pressure valve 33 into the tank 27.

The bypass valve 34 in the bypass line 40, together with the input pressure valve 37, provision is made to control the flow rate through the condenser 20. This suspension 27 has a suspension population of 53. It has a cleaning port 52 and a ventilation hole 48.

The suspension inlet pressure, the concentrated suspension outlet pressure, and the clarified liquid pressure are determined by the valves 37.3 and 37.3. 3 and 22. During the concentration mode, valve 26 is closed and valve 26 is closed. The valve 55 is open and the valve 30 is set in the passage (a).

In embodiments of the invention, the pressure within the concentrator shell 20 is After post-washing with clear liquid, the filter air is removed within the specified time for the concentration mode. It is set to remove gas inside the hole.

The liquid generated from valve 22 is used as an input to programmable controller 31. It is monitored by a flow sensor 32 and a parameter sensor. this The controller 31 sets preset values of time and flow rate to initiate the discharge cycle. is compared with the actual flow rate of the clarified liquid.

In an embodiment of the invention, determining the approximate time to discharge the concentrator 20 There are two criteria for this.

The first criterion is the release rate of the clarified liquid, reduce it to a predetermined value and set this rate. do. The second criterion is the time for the controller to discharge at regular time intervals. child The second criterion is for feedstock suspensions where the liquid flow rate does not decay very rapidly. More suitable.

The substantially dry gas is supplied to a gas pressure control valve 24 controlled by a solenoid 26a. , a gas flow valve 25 and a gas stop valve 26 via a line 23 in the discharge mode. installed in the system for a while. To effect evaporation (i.e. cooling), this gas is Must be saturated with respect to liquid vapor at operating temperature. Clear liquid infiltration/output line A hole cooling discharge line 60 connected between the solenoid 4 and the large air output section 61 3a and a hole cooling stop valve 46 controlled by a hole cooling check valve 46. . A system connected between supply input line 29 in line 23 and shell cooling change valve 42. well cooling line 63.

It has a shell cooling check valve 45. This shell cooling change valve 42 is a solenoid The input port is controlled by the input port 42a and has multiple functions detailed below. It has paths (a) and (1)).

In order to effectuate the discharge, the programmable controller 31 is configured to control the variable volume clarified liquid. Lifting and gas release means remove material from each fiber as well as from the system. Valve 22 is closed and valve 26 is opened to allow release.

The solenoid valve that closes the valve 43 and changes the output passage of the three-way valve 60 to passage (b) discharge the system by activating the ports 22a, 26a, 43a and 30a. Set to mode.

If the temperature from the sensor 44 to the programmable controller 31 is lower than the preset value, If the hole cooling time is also high, this programmable control will Set each solenoid so that valve 22 is closed, valve 43 is open, valve 41 is closed, and valve 26 is opened. Rapid evaporation of each hollow fiber prior to backwashing by activating the noid Start hole flow with gas for cooling. This hole cooling gas can be held at The clear liquid in the cylinder 47 flows through the line 21 without being disturbed and , into the clear liquid line via valve 43. This hole cooling time is within safe limits. sufficient to reduce the temperature of each fiber. This gas is a mass and the gas is saturated with a non-volatile liquid by lowering the heat equal to the specific temperature and temperature difference However, such cooling is slow, and the present invention substantially reduces the It is extremely effective when applied to highly volatile liquids and the latent heat of vaporization.

Water is ideal because of its large latent heat of evaporation. By operating at high temperatures There is a very small loss in production time compared to the time saved per day. 1. It usually takes 5-20 seconds to cool the water. Clean better It is possible to Adding the most expensive equipment because it already exists for other purposes The cost of addition is extremely small.

The programmable controller 31 closes the valve 43 and switches the valve 60 to the passage (b). Solenoids 45a and 30a are actuated to remove all liquid in each pore. each in the opposite direction to normal operation to displace the pores and expand all pores. Empty the contents of the device under gas pressure across the membrane and into each hole through valve 26. However, operating the electrically controlled clarified liquid hold up cylinder 47 The concentrated release is started.

After this hold-up cylinder 47 is empty.

This programmable controller 31 is used for cleaning fiber and shell concentrates. The gas release continues through the larger pores and the valve 26 is closed for this release cycle time. Open the door.

To make gas release more constant through each large pore along the length of the narrow fiber. For this purpose, after the hold up cylinder 47 is emptied, the hole check valve 46 and the hole stop Gas via stop valves 43 (these were opened by programmable controller 31) It is preferable to remove the .

This controller 31 sets the gas pressure inside the shell 27 to the maximum pressure by the gas pressure regulator 24. The shell shutoff valve 55 is closed by activating the solenoid 55a so as to close the shell shutoff valve 55. At the same time, the supply stop valve 41 is closed by activating the solenoid 41a. Ru. Valve 55 is opened by controller 31 for a predetermined gas release time.

At the end of the discharge cycle time, the programmable controller 31 The above procedure is followed except that the valve remains closed until the door-up cylinder 47 is filled with suspension. Change the system to concentrate mode.

For some suspension processes, it is necessary to pass the gas through the shell side of each fiber. Therefore, it would be preferable to cool each fiber. Program from sensor 44 Temperature to Mable controller 31, theta other conditions requiring a backwash cycle and above the preset limits, the fiber temperature is set to an optimal safe level. Valve for preset time as shell side cooling time which is sufficient to reduce 41 (closed), valve 26 (open), and valve 42 (path a side), the shell side Start cooling cycle. At the end of this shell-side cooling time, this program The controller controls valve 22 (closed) and valve 42 (passage side) for backflow cycle time. This will start the backwash cycle. At the end of this backwash cycle , this programmable controller returns the system to enrichment mode, as described above. .

A 10% solution of raw cane sugar is the fifth It was filtered using the device shown in the figure.

Here, an average transmembrane pressure (TMP) of 75 kPa and a temperature of 25 °C were used. temperature. Also here, additional There is no osmotic backflow. Air backflow is 700 kPa for 6 seconds every 30 minutes. there were. The permeability after 20 hours at 25°C is 30 L/sq, m , /hour.

The temperature of the raw material then rose to 98°C, and its permeability immediately increased to 80 L/sq1 m,/hour, but in experiments the fiber became excessively soft at 80°C. Therefore, backflow was not attempted at 98°C. The preferred temperature range for this backflow is 6 It was decided to maintain the temperature between 0°C and 65°C.

In shell cooling mode, 24 liters of air per minute is drawn due to the high latent heat of the evaporated water. By passing it through, the temperature of the fiber goes from 98°C to 60'O in 6 seconds. It descends and is cooled. Therefore, this backwash cycle is fully accomplished.

Example 2: Example 1 was repeated, but this time a wet sample of 3000 fibers at 98°C was used. After the hot suspension in the shell is emptied, the fiber bundles are removed to replace the infiltration. The tubes were cooled by passing 24 liters of air per minute along each hole. child The temperature of each fiber decreased to 65°C in 9 seconds.

From the foregoing description, one can see that the present invention provides a rapid, uniform and precisely controlled cooling method. It will become clear that This cooling is preferably by evaporation, but if Consistent with the need for this device, the feed suspension does not contain volatile substances.

Each fiber is cooled to provide optimal cleaning and production rates for the concentrator. , controlled to suit the flexible properties of each fiber. The cooling method of the present invention By using existing equipment with cross-flow type hollow fiber separators, is easily accomplished and controlled.

Example 3: The device shown in Figure 5 is a 0.2 micron car per square meter with a transmembrane pressure of 100 kPa. It was used to filter tap water supplied through the tridge. This flux is continuous at each temperature considered by periodic air wake and average flux rate. continued. As expected from the decrease in viscosity, the flux is more than twice as high as the temperature. , was raised from 10°C to 50°C. Values that allow operation at the highest temperature within the possible range. It is clear that there is.

The results of this example are graphically shown in Figure 6, which clearly shows the dependence of water flux on temperature. It is indicated by f.

Example 4: The device shown in Fig. 5 operates at 2.5 g at a transmembrane pressure of +50 kPa and at 42°C. It was used to filter a bentonite suspension of ram/l and the results are shown in Figure 7. Shown in the graph. The process and equipment of the present invention and high temperature (low temperature strain temperature of fiber) Even in the notoriously difficult bentonite suspension, the overall Clear liquid can be produced continuously at a high level.

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Claims (8)

[Claims] 1. The suspension is provided within a shell or housing of flexible and microporous added to the hollow fibers and retained on or within each fiber or within the shell. Each solid is released by a pressurized backflow of clarified liquid following a pressurized backflow of gas, and each A suspension treatment method in which the hollow fibers are cooled before the start of pressurized backflow. . 2. A method for concentrating each solid substance in a suspension comprising the following steps: (i). shell or housing The suspension is applied to the outer surface of each flexible and microporous hollow fiber within the ring. In addition, thereby: (a). A suspension is passed through each fiber to be exited as a clear liquid through the fiber holes. (b). At least some solid matter is on each fiber. or within the shell, or otherwise removed from the shell with the remaining liquid. is retained, along with each non-retained solid object. (ii). Finish the suspension flow, then cool each hollow fiber, and , (iii). Shape each retained solid by adding it through the fiber hole. Emit from: (a). Expands virtually all pores to wash out all retained solids a pressurized liquid that penetrates substantially all of the pores, (b). Expand these pores and remove all solids trapped in these pores. , remove all solids from the shell to an external collection area and Pressurized gas passes through each enlarged pore to clean the outer wall of each fiber. Equipped with a 3. Claim 1 or 2, which includes the application of pressurized gas consisting of the following step: Method of description: (a). each fiber hole to displace all fluid from each fiber hole. Gas is initially added at a pressure below the bubble point on each wall of the tube, (b). (c) sealing the outer surface and shell of each fiber with a liquid; each fiber Increase the gas pressure above the bubble point on each wall of (d). Allows trapped gas to escape substantially and consistently through each fiber wall To do this, release the liquid seal. 4. Each fiber is cooled by passing gas through each hole in each fiber. A method according to any one of the preceding claims. 5. Each fiber is cooled by adding gas to the outer surface of each fiber. The method according to any one of claims 1 to 3, wherein: 6. Each step of this process consists of repeated cycles of solids retention, fiber cooling, and solids release. Claim 1 or 2 is carried out as a continuous process using a ring. The method described in section. 7. Concentrator for concentrating fine solids in raw material suspensions consisting of: (i). one shell and (ii). Each flexible and hollow polyester with micro pores is provided inside the shell. Marfiber; (iii). Supplying pressurized raw material suspension to the outside of each fiber and means for (iv). means for recovering clarified liquid from the fiber holes; (v). (vi) means for cooling each fiber; Inside and outside of each fiber Fluid and liquid followed by gas under pressure are applied to each fiber hole to achieve membrane cleaning. , a liquid pressure sufficient to expand substantially all pores of each fiber; and Remove any solids retained therein and remove all solids from the shell to an external collection station. gas to clean the inside of the shell and the outside wall of each fiber. a means for applying sufficient gas pressure to ensure that the gas penetrates the larger pores. 8. Additionally, gas accumulates within each hole at pressures above the bubble point in each fiber wall. Considering that the liquid from each fiber hole is replaced by pressurized gas, the shell each fiber wall with a means for sealing the relatively incompressible feedstock suspension within the Patent having means for effecting rapid release of gas for substantially and constant penetration A concentrator according to claim 6.